How did the transition from a world of empire to a global international system organised around the sovereign state play out? This article traces the transition over the past two centuries through an examination of membership debates in two prominent intergovernmental organisations (IGOs). IGOs are sites of contestation that play a role in the constitution of the international system. Discussions within IGOs reflect and shape broader international norms, and are one mechanism through which the international system determines questions of membership and attendant rights and obligations. The article reveals that IGO membership policies during this period reflected different compromises between the three competing principles of great power privilege, the ‘standard of civilisation’, and universal sovereign equality. The article contributes to Global IR as it confirms that non-Western agency was crucial in bringing about this transition. States in Africa, Asia, and Latin America championed the adoption of the sovereignty criterion. In this, paradoxically, one of the core constitutional norms of the ‘European’ international system – the principle of sovereign equality – was realised at the hands of non-European actors.

Drawing on a notable example of a non-Western normative initiative, Brazil’s ‘Responsibility while Protecting’ (RwP), this article contributes to broadening the scope of the norm dynamics literature beyond its common Western-centric focus. Post-2011 Libya intervention, Brazil proposed RwP to clarify what ‘using force’ means under the Responsibility to Protect (R2P) banner, but then withdrew from visible norm sponsorship, only to return to this as part of a collective exercise to institutionalise R2P at the United Nations. First, the article highlights the significant role of non-Western agents whose contributions usually go overlooked, yet carry the highest potential to address the legitimacy deficit of norms like R2P. Second, the article proposes adding a new conceptual tool when investigating the role of agency in norm dynamics, one that incorporates a wider range of norm ‘shaping’ processes and highlights enabling, contingent circumstances. The latter, is argued, best captures the anomalies in contemporary norm contestation. This is illustrated through an empirical analysis of the conditions under which Brazil was able to advance RwP, despite the subsequent emergence of unfavourable circumstances. This article emphasises how significant an alignment of enabling circumstances is to non-Western agents in terms of shaping norm contestation and normative exercise completion.